1. Field of the Invention
The present invention relates to a novel polypeptide which has secretion enhancing activity on lacrimal and parotid gland cells, monoclonal antibodies thereto, and methods of diagnosing Sjogren's syndrome using these antibodies.
2. Discussion of the Background
Sjogren's syndrome is the second most common autoimmune disease and is a triad of disease including rheumatoid arthritis and dry eye.
Dry eye, the ocular component of Sjogren's syndrome, is a condition of the eye and or the adnexa that usually causes a feeling of discomfort such as ocular dryness, grittiness, burning, soreness or scratching, to the patient. Many theories have been offered to explain the possible causes of dry eye. These theories range from the simple to the complex and include inadequate Meibomian gland secretion, insufficient tear volume, mucous deficiency, evaporative losses from the tear film and failure to form an adequate tear film. Proposed causes for dry eye, treatment and symptoms are described in a compendium of papers on the subject edited by Holly, The Preocular Tear Film In Health, Disease, and Contact Lens Wear, The Dry Eye Institute, Lubock, Tex., 1986, incorporated herein by reference.
Despite these theories, the cause of dry eye has yet to be definitely determined. Currently, dry eye is treated with ophthamalic solutions which represent "artificial tears". Such compositions are methods of treatment are described in U.S. Pat. No. 4,914,088. There remains a need for understanding the cause of dry eye such that better treatments can be developed.
Despite the large population affected by Sjogren's syndrome, to date no accurate diagnostic assay is available. Rose Bengal staining of nasal conjunctiva cornea and temporal conjuctivaassessed with a semiquantitative scoring system is described in Ann. Ophthalmol. 5:859, 1973. The tear film breakup time test assesses stability of tear film as described in Arch. Ophthalmol. 89:103, 1973. Schirmer test assesses the ability of the lacrimal gland to produce reflex tears as described in Am. J. Ophthalmol. 66:70, 1968. The tear film osmolarity test is described in Arch. Ophthalmol. 96:677, 1978. None of these tests are especially sensitive or specific. Accordingly, there is a also need for accurate diagnostic means.